Product Specifications:  Sulfur Modified Iron (SMI-III®)  SeleniumZero

Description and Use

SMI-III®/SeleniumZero is a patented modified iron media developed to remove selenium and other contaminants from water.  It is a granular media consisting of porous, solid grains that are used as a chemical adsorbent and/or reductant.  SMI-III® removes both selenate and selenite forms of selenium from a variety of waters, to concentrations below the 2 micrograms / liter (μg/L) detection limit.  The total adsorption capacity of SMI-III® for selenium will depend upon empty bed contact time, pH and other water quality parameters.  SMI-III® can also remove contaminants such as arsenic, nitrate, copper, trichloroethylene (TCE), mercury, and hexavalent chromium.  Pilot studies should be conducted for final determination/confirmation of design and removal capacity.  Please contact SMI-PS Inc. for more detailed information and design requirements.  SMI-III® is NSF Standard 61 certified.


  •  Can achieve extremely low level of Selenium for discharge permits.
  •  Can be used as a polishing step after biological treatment for Selenium.
  • Spent media can be sent to landfill without further treatment.

Application Information

Upflow Contactor Only:
1.  Recommended Range of Operating Conditions:

  • Max. head loss: +6 psi
  • Max. operating temperature: 90° F
  • Typical bed expansion at 15 gpm/ft² backwash flow: 20%
  • Typical head loss at 5 gpm/ft²: 1.0 psi

2. Recommended Influent Water Quality

  • Preferred pH: pH 5 – 9
  • Dissolved oxygen: Low concentrations are preferred
  • Suspended solids: Minimize (1.0 < NTU). No oxidants: e.g., chlorine, hypochlorite, ozone, peroxide, ferric chloride, permanganate, chloramines or other oxidants.


Physical Form:  Solid – Granular Bulk Density : ~1.91-2.54g/cm³ (~120-160 lbs/ft³)  [Note: Bulk density varies depending on packing]  

Color:  Brown to black Particle Size : 20 – 80 mesh  

Adsorption Capacity : Typically 0.7-1 milligram Se/gram SMI-III®.

Materials Compatibility

SMI-PS Inc. can assist in specifications for vessel/piping selection and design.


SMI-III® is available in 55 gallon (~1000 lbs) or 16 gallon (~290 lbs) drums.  Details are available on request.

Maximum storage temperature: 90° F.   Storage period: 60 months.  Store dry until ready for use. If wetted material is taken off line temporarily, keep the media submerged in a closed container/vessel to prevent oxidation of the media and perform periodic backwash of media bed.

Safety Information

Detailed information on the product described in this leaflet can be found in our relevant health and safety information (Material Safety Data Sheet). Please contact us for further information.